Electron discharge device utilizing cavity resonators



Get. 26, 1948. 1 s. NERGAARD ELCTRON DISCHARGE DEVICE UTILIZING CAVITYRESONATORS Filed March 27, 1944 2 Sheets-Sheet l @et 26, 1948. 1.-. s.NRGAARD 2,452,318

ELECTRON DISCHARGE DEVICE UTILIZING CAVITY RESONATORS Filed March 27,1944 2 sheets-sheet 2 ATTORNEY Patented Oct. 26, 1948 ELECTRON DISCHARGEDEVECE UTILIZING CAVITY RESONATORS Leon S. Nergaard, Princeton, N. J.,assigner to Radio Corporation Iof America, a corporation of DelawareApplication March 2v, 1944, serial No. 528,195

7 Claims.

"Myinvention relates to electron` discharge devices and circuitstherefor and particularly to such devicesl and circuits useful at ultrahigh frequencies.

The present application is directed to an im provement over the deviceand circuit shown in my co-pending application, Serial No. 514,206,iiled December 14, 1943, and assigned to the same assignee as thepresent application.

Electron discharge devices using cavity resonators are used at ultrahigh frequencies. In the triode type, the electrodes are usuallyarranged in the order of cathode, grid and anode, and may have radiallydirected supports and lead-ins extending through the envelope andcontacting the cavity resonator circuits. For example, in the triode aninput cavity resonator, which may be of the coaxial line type, isconnected between the cathode and grid, and the output resonatoris'connected between the grid and anode. In another type oftuberei'erredto as an inductive output tube, the electrodes are in theorder of cathode, grid, accelerator and collector. The input resonator,usually ofthe coaxial line type, is connected between the cathode andgrid, a second resonator is connected between the grid and acceleratorand the output resonator is positioned between the accelerator andcollector.` The resonator connected .between the control grid andaccelerator or screen is used to bring the accelerator to cathodepotential for radio frequencies and is used for regeneration tocompensate for the diode loading. At ultra high frequency it is desiredto so construct and arrange the leads to tube electrodes that they haveas low inductance as possible, or, alternatively, to so arrange themthat they comprise conductors of transmission lines which may be joinedwith an external circuit. Leads of triodes and of the triode section ofinductive output tubes have been brought out in the same space sequenceas the electrodes have within the tube, namely the sequence cathode,grid andanode, or in the case of the inductive output tube, theaccelerator and collector. Because of this arrangement it is necessaryto use the so-called grounded grid circuit, which is characterized byhaving a circuit between the grid and plate, or grid and accelerator.The disadvantages of this arrangement are, rst, the full diode loadingof the tube appears across the input circuit. This requires a higherdriving power and results in a low power gain. Second, in the inductiveoutput' tube the circuit between the grid and accelerator is used tobring the accelerator to cathode potential as far as radio frequency isconcerned,v or to introduce regeneration to compensate for the diodeloading. Be-

cause regeneration tends to be unstable, tuning` of the circuit iscritical. It is desirable to eliminate diode loading and to remove thecircuit between grid and accelerator. This would simplify tuning of thetube circuit without sacricing performance.

It is, therefore, the principal object vention to provide an improvedform of an elec-.- tron discharge device and circuit useful at ultrahigh frequencies.

It is another object of my invention to pro-`A Vide such a deviceutilizing cavity resonators but in which the usual diode loadingassociated with tubes of this type is eliminated, and in which circuitsrequiring critical tuning are made unnecessary.

It is a further object of my invention to pro vide such a deviceutilizing cavity resonator circuits in which the grounded grid circuitis avoided.

The novel features which I believe to be characteristic of my inventionare set forth with particularity` in the appended claims, but the in-lvention itself will best be understood by reference to the followingdescription taken in con nection with the accompanying drawing in which,

Figure 1 shows a longitudinal section of an electrondischarge device andcircuit made ac cording to my invention, Figure 2 is an enlarged' detailsection of the electrode arrangement of the device shown in Figure4 1,Figure 3 is a transversesection taken along the line E- of Figure 2 andFigure 4 is a diagram showing an equivalent circuit of the device shownin Figure 1.

' In accordance with my invention I provide an electron discharge devicehaving an elongated indirectly heated l0, control grid assemblycomprising envelope 9. containing an cathode wires l, collar lli,conductor 6B, and cone-v shaped collar member tl, acceleratingelectrode` of my Sine l tubular member 2| is closed at one end by theconducting member 22 and provided at the other end with an end wall 24.The device is tuned by means of the tuning short circuit 23. This inputcircuit is coupled between the cathode and the grid, the grid beingcapacitively coupled to the inner-member'ZDfinsulated from the grid ringby meansof the non-conducting collar 25, preferably of mica. The endwall 24 is provided with spring contact fingers 2B making directelectrical contact with'the cathode.

The output circuit comprises a second resonator including disc endmembers 30 and 3l electrically connected at their .peripheries by meansof the collar 32. The end wall 3l: is provided with collar 33 havingspring ngers 34 electri- 4 and a cavity resonator coupled between bothsaid conducting means.

2. An electron discharge device having an envelope containing a cathodeassembly, a hollow grid assembly and another electrode in the ordernamed, said grid assembly including a colla-r supportingfnmeanssupportedI from said envelope, said cathodelassembly beinginsulatinglysupported entirely within said grid assembly and solely from said gridassembly, conducting means connected to said grid collar supportingmeans,

cally contacting the accelerator .conducting ring l1; the other wall 30is capacitively coupled to the input resonator through the micainsulating A ring 35. Thus the accelerator and resonator may bemaintained` at a different voltage with respect tothe input circuit. Theinput circuit may be maintained at ground potential since it is connected to the cathode.

In accordance with my invention I provide novel V.cathode andgridsupports having crossedover connections which permit the cathode and larissupported by means of the rodl and insulating bead construction 43,which securely and firmly supports the cathode within and coaxially ofthe grid. Radially directedwires or conductors 4B extend between leadsV4l] and electrically connect they cathode with the cathode ring. l5.Thus an improved type of cross-over cathode and grid lead constructionis 'provided whicheliminates the objectionable features above Vmentionedof the usual electrode arrangement. .A cathode heater lead 42 extends tothe exterior of the envelope through which it is sealed. The other sideof the heater is electrically connected to the'-l cathode.

In Figure 4 is shown the equivalent clrcuitof the device shown in Figure1, the numerals indicatingithe same elements as in Figure 1.

While I have indicated the preferred embodi-l.

1'. An electron discharge device having an en-V velope containing acathode, a hollowv grid assembly and another'Y electrode, vall in ordernamed, said grid assembly including a collar member, said cathode beinginsulatingly supported solely from said grid assembly and enclosedentirely within said grid assembly, conducting means connected to saidcollar member, conducting means connected tos'aid cathodeand-extending'through said grid l assembly but out of contact therewith,

conducting means connected to said cathode and extending through but outof contact with said grid assembly and `a cavity resonator coupledbetween both of said conducting means.

3. An electron discharge device having a cathode, a hollow grid assemblyand another electrode in the order named, said cathode being supportedwithin said grid assembly and coaxially of said grid assembly by meansof insulating spacer4 members, radially extending conducting meansconnected to said cathode and extending through but out of contact withsaid grid assembly,I and a cavity resonator coupled between said gridassembly and -said cathode conducting means.

4. An electron discharge device havinga cathode, a hollow grid assemblyand another electrode in the order named, said vgrid assembly includinga conducting collar, a conducting conelike member connected to one endof said collar, said cathode being mounted axially of said collar, andinsulatingly supported within said grid and collar, radially-extendingconductors extending between said cone-like member and saidcollar `andconnected to said cathode, and a cavity resonator vcoupled .v betweensaid grid and said cathode, one side of said cavity resonator beingelectrically connected to said radially extending conductors and theother side of said cavity resonator being capacitively coupled to saidconelike member. y

5. An electron discharge device having an envelope containing a cathode,a hollow grid and 'another electrode in the order named, ring-likeconducting members sealed through said envelope and spaced along saidenvelope, said grid including a collar having a ared skirt thereon and-a oraminous portion supported thereon, said skirt. being electricallyconnected to one ofysaid ringilike conducting members, said cathodebeinginsulatingly supported within said collar and grid, leads connectedto said cathode and extending between said collar and said foraminousportion but'out of contact therewith and electrically connected toanother of said ring-like conducting members, and a cavity resonatorcoupled between said grid and cathode ring-likel conducting members, onesidel of said cavity resonator being electrically connected to aring-like conducting member and the other side of the cavity resonatorbeing capacitively coupled to the other ringlike Vconducting member.

6. An electronV discharge device having-a cathi ode, a hollow grid andanother electrode inthe tending between said collar andsaid foraminousportion and; collar but out` of contact therewith and electricallyconnected to another of said ringlike conducting members, and a cavityresonator coupled between said grid and cathode ring-like conductingmembers.

'7. An electron discharge device having an envelope containing acathode, Va hollow grid and Ianother electrode in the order named,ring-like conducting members sealed through said envelope and spacedalong said envelope, said grid including a collar having a flared skirtand a foraminous portion supported at one end of said collar, said skirtbeing electrically connected to one of said ring-like conductingmembers, said foraminous portion being supported on said collar by aplurality of rod-like conductors spaced around said collar, said cathodebeing insulatingly supported Within said grid, leads connected to saidcathode extending between but out of contact with said rod-likeconductors and electrically connected to another of said ring-likemembers,

and a cavity resonator coupled between said grid and cathode ring-likeconducting members, one side of said cavity resonator being electricallyconnected to said cathode ring-like conducting member and the other sideof .the cavity resonator being capacitively coupled to said gridringlike conducting member.

LEON S. NERGAARD.

REFERENCES CITED The following references are of record in the le ofthis patent:

UNITED STATES PATENTS Number Name Date 2,128,232 Dallenbach Aug. 30,1938 2,190,511 C'age Feb. 13, 1940 2,287,845 Varian et al June 30, 19422,353,743 McArthur July 18, 1944 Goodohld Feb. 19, 1946

